what is the reasonably ideal payback period in your mind?

I hear you . the price of those dedicated miners are outrageously high nowadays. we will be working hard to control the price to below $200, and performance as good as RX 570 type of GPU.

it is a valuable advice, thanks! just see what happened to monero when antminer x3 is introduced to market...

good point, nobody wants to invest in that much $$$ for a miner which has low resale value. the reason i said $500 is that price range i can manage to compete with the GPU miner at 1/10 of its power consumption. but maybe that's not what miners want? you would prefer $100 fpga miner with only 1/4 of GPU hash rate?

Thanks.

you are right, but technically, from the hash/power efficiency perspective, the gpu can never beat fpga, just like fpga can never be faster than ASIC (which also requires millions $ investment). but like you said gpu is generic and has resale potential. but fpga is versatile, we can custom build the product the way miners want. what would make you to buy a fpga miner? does any of the designs i proposed appeal to you? thanks.

HI thank you for your interest, I will definitely keep you updated when rubber hits the road! right now we are still working on prototyping our miner design on development boards from different fpga vendors. the fpga devices nowadays are made very power efficient, if a typical gpu takes 150W when mining, i think it is very likely to achieve the same level of hashrate with only 15W power intake.
the price is just a rough number as we haven't run through all the numbers with our suppliers.. technically it would be little tricky to implement a dev fee, and morally i am against it  (no offense) I wouldn't sleep well to take a percentage of miners' hard mined coins...

Yes please take a look at the big and tiny designs i proposed in another reply i would like to know what miners want the most, time has changed since bitcoin fpga era, we should consider changing the design if the is demand from miner community. thanks.

thank you for your valuable inputs. I am a GPU miner myself and it would also be my no.1 concern of no resale value when buying those dedicated fpga/asic miners.
so what would make you buy a fpga miner? you mentioned the price, currently there are two designs in my mind but i don't know which one customers would prefer:

1. a "big" fpga board with 2 or 4 cores on it, the hash power can beat a graphic card, with only a quarter of its power consumption. priced around $400-$800 (depending on the number of cores), most efficient hash/power and better hash/cost perhaps.
2. a "tiny" fpga mining usb stick. It would look a usb flash drive with heatsink on it (as showed in the link below). it has only one fpga core on it, maybe only a quarter of the GPU miner hash power, but power consumption is tiny as well, as it is powered solely from the USB. priced around $100 (i haven't run through all the numbers yet, just rough one). potentially you can connect multiple of those sticks on a usb hub with good power source. you can also take it with you and plug in your laptop and mine anywhere you want! this would be less efficient in hash/power and hash/cost if you compare to the big one though.
https://www.amazon.com/GekkoScience-2-Pac-Compac-Bitcoin-BM1384x2/dp/B06XBWK2W5/

I agree with you there are so many talented fpga/asic programmers here, but the design, manufacture and validation cycles may cost time and money. during which time we can constantly improve our design to make it more competitive.

Hi everyone, I would like to know your opinions on the FPGA miners for altcoins. My partner and I have been working on a FPGA miner project for an altcoin(sorry i can't reveal now, but not a very popular one), after being fully optimized we believe the fpga miner should be able to achieve the same level of hash power as of a mid-range graphic card with only 1/10 of the power consumption. It would essentially look like one of those early day bitcoin FPGA miners, with 2 or more FPGA "chips" on a PCB board (depending on the demand), like the one in this link
http://fpgamining.com/. The other beauty of FPGA miners is that a cheap raspberry pi can be used as the host to drive all FPGA miners connected to it via USB cables, there is no GPU -like rigs needed.
Due to the development, custom board design and manufacture the final price might end up in the $500 range. Do you think someone would buy such a product for mining nowadays? Just want to hear your general opinions on it, as both of us are relatively new to the crytocurrency and didn't experience the fpag miner era of bitcoin.

Any suggestion is appreciated!